Pollinator-Friendly Lawns: Flowers or No Flowers?

April 28, 2013

TURF is a $25 BILLION USA INDUSTRY, said Nastaran Tofangsazi of the University of Florida (Apopka, FL), a sex pheromone researcher looking to complement biocontrols like beneficial Beauveria bassiana fungi and Steinernema carpocapsae nematodes to control the browning and uneven grass growth caused by tropical sod webworm (Herpetogramma phaeopteralis) in Florida’s $9 billion worth of turfgrass. Also at the Entomological Society of America (ESA) annual meeting, Auburn University’s R. Murphey Coy noted that the USA’s 164,000 km2 (63,320 square miles) of turf is the USA’s most irrigated crop. Turfgrass irrigation consumes 300% more water than corn; plus 4.5 pounds (2 kg) of nitrogen per 1,000 square feet (93 m2).

Alabama is among the top USA turfgrass-producing states, and Auburn University researchers are looking to reduce turfgrass water, nitrogen and iron inputs by colonizing grass seeds and roots with easy to apply sprays of plant growth promoting rhizobacteria (PGPR). Blends of PGPR species such as Bacillus firmis, Pseudomonas and Rhizobium in turfgrass and cotton induce systemic resistance to pestiferous Fusarium fungi and triple parasitic wasp biocontrol of the caterpillar larvae of moth pests like fall armyworm (Spodoptera frugiperda).

Not everyone is a fan of turfgrass lawns, and before the modern chemical era lawns were more like fragrant flowery meadows. “Agricultural experts and agribusiness are bound by the idea that even land that has lost its natural vitality can still produce crops with the addition of petroleum energy, agricultural chemicals, and water…considering this form of agriculture to be advanced,” wrote Japanese agriculturist and philosopher Masanobu Fukuoka in the book, Sowing Seeds in the Desert (edited by Larry Korn).

“When I suggested that it would be a good idea to plant fruit trees to line the streets in towns and cities and to grow vegetables instead of lawns and annual flowers, so that when the townspeople were taking a walk, they could pick and eat the fruit from the roadside, people were surprisingly enthusiastic,” said Fukuoka. “When I suggested that it would be good to scatter the seeds of clover and daikon on the existing lawns so that in two or three years the clover would overcome the lawn and the daikon would take root amid the ground cover, interestingly, it was the Asian people and Asian-Americans who said they would try it right away. Most Americans would just laugh and agree with the theory, but they were cautious about putting it into practice. The reason, I believe, is that it would challenge their adherence to ‘lawn’ culture. If they cannot overcome this prejudice, there will be a limit to the growth of family gardens in the United States.”

“It seems that the main goal in the life of the average American is to save money, live in the country in a big house surrounded by large trees, and enjoy a carefully manicured lawn,” wrote Fukuoka. “It would be a further source of pride to raise a few horses. Everywhere I went I preached the abolition of lawn culture, saying that it was an imitation green created for human beings at the expense of nature and was nothing more than a remnant of the arrogant aristocratic culture of Europe…Because residential lots are large in the United States, a family vegetable garden can provide for all the food needs of a typical family, if they are willing to do the work. In Japan, a residential lot about a quarter acre would be enough to allow near self-sufficiency and provide a healthy living environment, but I learned—to my envy—that in many suburban and rural areas of the United States, people are not allowed to build houses on small lots.”

On closer inspection, modern American lawns are more often a biodiverse mixture of turfgrass and flowering plants like clover and dandelions. Kentucky bluegrass lawns may be 30% white clover, which favors native pollinators like bumblebees. Clover and dandelion flowers attract honey bees, bumble bees, parasitic wasps that kill pests, hover flies (syrphids) that eat aphids, and carnivorous rove and ground beetles eating snails, slugs, caterpillars and other pests. Nonetheless, tons of herbicides go onto USA lawns to eradicate clover and dandelions as weeds, often as part of fertilizer and insecticide mixtures.

Turf biodiversity is all well and good, but only as long as the clover and dandelion flower nectar is pure and uncontaminated by pesticide cocktails. Lawns laden with clover and dandelion flowers provide bees and beneficial insects with “a big gulp of nectar,” the University of Kentucky’s Jonathan Larson told the ESA annual meeting in Knoxville, Tennessee. When those “big gulps of nectar” are laced with certain neonicotinoid pesticides, the effects can ripple through the ecological food chain.

When turfgrass pesticide labels say, ‘Don’t treat flower heads,’ “Follow the label to the letter of the law” to avoid poisoning pollinators, said Larson. Or get rid of the flowering plants in the lawn by mowing the turf before spraying. Or delay pesticide sprays until after clovers, dandelions and other lawn flowers have finished flowering. Clover control in lawns using herbicides is difficult, and usually not feasible, Larson told the ESA. Hence, mowing is the preferred strategy for removing flowering lawn weeds before spraying pesticides.

In enclosure experiments with tents confining bees in the turf, mowing the turf before pesticide treatment mitigated the problem, resulting in more bees and more honey. In 2012, bees were tented on clothianidin-treated turf for 6 days and then moved for 6 weeks to a Lexington, Kentucky, horse ranch with unsprayed turf. Clothianidin reduced the rate of bumble bee weight gain, but at the end of 6 weeks the bees were starting to catch-up. But overall, the 6-day pesticide exposure still resulted in reduced bumble bee weight gain, less foraging and reduced queen and hive reproduction several weeks later. Chlorantraniliprole, which has a different mode of action (muscular), did not produce these adverse effects. Larson also told the ESA that clothianidin, a widely used neonicotinoid turf pesticide, also reduces decomposers (detritivores) like soil-dwelling earthworms and springtails more than chlorantraniliprole.

Besides supporting more soil life, more biocontrol organisms, and healthier crops of pollinating bees, you get a healthier turfgrass lawn if you do not need pesticides and do not have to mow so often. “Mowing height is an easily manipulated cultural practice that can have an impact on ecological conditions,” Samantha Marksbury from the University of Kentucky, Lexington, told the ESA. “Taller grass usually supports a more diverse ecosystem and increases natural enemies. Increasing cutting height stimulated deeper roots, yielding a healthier turf with less need for insecticide. Higher mowing height decreases need for irrigation and the canopy prevents water loss.”

Taller turf (raised mowing height) also tends to be more robust and more tolerant of white grubs. Nevertheless, about 75% of turf is lush residential monocultures (mostly one grass species) that is heavily fertilized, dosed with chemical herbicides and frequently mowed, Emily Dobbs of the University of Kentucky, Lexington, told the ESA. However, the ecology of grass cutting or mowing gets quite complex and has seasonal variations. In May, turf with a low mowing height (2.5 inches; 6.4 cm) was hotter, drier, and had the most predatory ground beetles, rove beetles and spiders. Later in the season and Sept/Oct, turf with a higher mowing height (4 inches; 10.2 cm) was cooler, wetter, and had the most predators.

Historically, in the Middle Ages in England, going back many centuries (even before Chaucer) before the age of chemical farming and gardening, lawns were “flowery meads” with roses, violets, periwinkles, primroses, daisies, gillyflowers and other colorful, fragrant flowers interplanted right into the turf. The idea of planting a lawn with one species of grass made no sense, though a camomile lawn or plot came into being for infirmary gardens in England after 1265, as this medicinal aromatic plant helped other plants growing nearby in poor soils and grew faster the more it was trodden.

“There were no flower-beds of the sort familiar to us,” wrote Teresa McLean in her 1981 book, Medieval English Gardens. “The simplest type of flower garden was the flowery mead, wherein low-growing flowers were planted in turf lawns, sometimes walled, sometimes left open, to make a beautiful domestic meadow. The flowery mead was the locus amoenus of God’s beautiful world.”

“Trees were often planted in raised turf mounds, surrounded by wattle fences, which doubled as seats,” wrote McLean. “Medieval lawns, unlike modern ones, were luxuriously long, and full of flowers and herbs; they were fragrant carpets to be walked, danced, sat and lain upon. What modern lawn could find a poet to write about it as Chaucer wrote about the one in the Legend of Good Women?

Upon the small, soft, sweet grass,
That was with flowers sweet embroidered all,
Of such sweetness, and such odour overall…”


Native Bees Pick Up Pollination Slack (Combating Colony Collapse)

May 3, 2012

HONEY BEE COLONY COLLAPSE Disorder (CCD) is a murky headline catch phrase, a scientific-sounding term that is almost a euphemism, to describe a population decline. In other words, there are fewer honey bees than there used to be, which is bad for agricultural crops dependent upon these domesticated insects for pollination.

Why a population decline is called a “disorder” is a bit beyond me, though it sounds almost clinical or medical. Perhaps that is the point; and calling it a disorder makes it a more respectable object of study and aids in obtaining funding and public support for research and finding a remedy. The declining human populations in Russia, Italy, Germany, Japan and other developed countries are not called a disorder; which perhaps implies an underlying value judgment. Might be nice to discover a Bed Bug Colony Collapse Disorder (BBCCD) to give cause for celebration. Though the acronym BBCCD in the Google search engine would confusingly yield CDs from the British Broadcasting Corporation (BBC).

Wikipedia makes it sounds like honey bees are being kidnapped: “Colony collapse disorder (CCD) is a phenomenon in which worker bees from a beehive or European honey bee colony abruptly disappear. While such disappearances have occurred throughout the history of apiculture, the term colony collapse disorder was first applied to a drastic rise in the number of disappearances of Western honey bee colonies in North America in late 2006…” If such occurrences have been happening throughout history, then the “disorder” sounds more like normality. In any case, times are tougher for those relying upon domesticated honey bees for crop pollination.

The interesting flip side of honey bee colony collapse disorder is the almost metaphorical return of the natives: Really a rediscovery and new appreciation of overlooked native pollinators like North American squash bees, digger bees, miner bees, sweat bees, bumble bees, and syrphid flies.

Whether you call it a disorder or a population decline: Nature abhors a vacuum or an empty ecological niche, like an absence or paucity of pollinating honey bees in a flowering agricultural ecosystem. Niches tend to get filled in nature, though the process may take years. With fewer honey bees (Apis mellifera is an introduced species in the Americas) in the fields, native bees hitherto ignored or overlooked are taking over the pollination chores on certain crops, according to research presented at Entomological Society of America (ESA) meetings.

“Nearly 4,000 species of native bees are found in North America,” said the University of Kentucky’s Amanda Skidmore. Integrated Pollination Management (IPM) or Integrated Crop Pollination, jargon phrases that sometimes popup at meetings, refers to managing crop ecosystems as habitats for native pollinators.

“In order to best utilize bees as pollination service providers, agro-ecosystems must be managed to attract and sustain them based on their natural history biological requirements,” Skidmore told the ESA. These habitat requirements include “energy (nectar), larval food proteins (pollen), and protected nesting sites (i.e. untilled earth, nesting boxes, dead plant matter).”

Native long-horned bees (Melissodes bimaculata) take up some of the slack from depleted honey bee populations in Kentucky by pollinating squash, melon and vegetable crops. Sweet alyssum (white-flowered variety), a flower interplanted in agricultural crops to promote biological control of pests by natural enemies, was heavily favored by the native pollinators; along with bee balm (Monarda didyma) and wood sage (Teucrium canadense). The idea is to plant a succession of flowering resources, including native wildflowers, shrubs and trees, to sustain native pollinators from very early season to late season. Research on habitat plantings is on-going.

Native North American sweat bees (Halictidae) and digger or mining bees (Andrenidae) are abundant pollinators of Michigan’s important blueberry crop in some locales, Michigan State University researcher Rufus Isaacs told the ESA. Nearby meadows “grow” sweat bee populations that move into blueberries to provide pollination services. Well-drained soils mean more nesting habitat for digger or mining bees that also pollinate blueberries. Several dozen wild native annual and perennial plants with varied bloom periods are being test-grown near Michigan blueberries to determine which best boost native bee populations and reduce the need for honey bee pollination.

Similar strategies for adding habitat for native pollinators are also being researched in crops as diverse as apples, cherries, squash and watermelons in regions as far-flung as Florida and California.

Moth-Eye Reflections

September 8, 2011

“ANTI-REFLECTION MOTH-EYE ARRAYS are now widely applied in panels of instruments, like cellphones and in window panes,” wrote Doekele G. Stavenga of the Department of Neurobiophysics at the University of Groningen (The Netherlands) in Functional Surfaces in Biology -Little Structures With Big Effects, Volume 1. The editor, Stanislav Gorb of the University of Kiel (Germany), thanked senior publishing editor Zuzana Bernhart (Plant Pathology and Entomology; Springer, Holland) for her “belief in this topic and her personal help.” Bernhart said that a big dose of the inspiration for the two book volumes came from what have become regular symposia on insect-inspired innovations at the Entomological Society of America (ESA) annnual meetings.

At nanotechnology events, insects and entomology are acknowledged frequently as inspiration. For example, at the California NanoSystems Institute on UCLA’s campus, Tomohide Takami, a researcher visiting from the Division of Quantum Phases and Devices at Konkuk University (South Korea), said “we have fabricated a bio-mimetic probe called ‘nano-mosquito’…to explore nano-world.” In a prior lecture Xiaodong Chen visiting from Nanyang Technological University (Singapore) noted: 1) energy storage devices, lightweight aerospace materials, and self-assembly inspired by diatoms and honey bee honeycombs; 2) Singapore’s waterfront Esplanade Theatres on the Bay is an architectural shape perhaps inspired by fly eyes and tropical fruit (durian); 3) moth eyes that are anti-reflective (so enemies do not see the glint of their eyes) and provide better vision at night and in fogs inspire solar cells that harvest more light.

“Anti-reflective moth-eye arrays could produce up to 12% more energy than those employing single layer anti-reflective coatings,” via “a reduction of up to 70% of the light reflected from the surface,” said Stuart Boden and Darren Bagnall of the University of South Hampton (UK) in their poster display (“Bio-mimetic nanostructured surfaces for near zero reflection from sunrise to sunset”). Via electron beam lithography and dry etching (subwavelength): “We have fabricated a range of moth-eye arrays in silicon. Reflectance measurements confirm the low reflectivity of these arrays over the visible and near infra-red wavelengths, making them excellent candidates for reducing reflection on solar cells.”

“Insects have facetted, compound eyes, consisting of numerous anatomically identical units, the ommatidia,” wrote Doekele Stavenga and his colleagues in the Proceedings of the Royal Society B (22 March 2006. 273(1587):661-667), a journal whose roots date back over 200 years to London in 1800. Back in the 1960s, researchers discovered that the outer surfaces of moth eyes had “an array of cuticular protuberances termed corneal nipples” which reduce light reflection to 1%. Thus, moth night vision is improved by allowing 99% of light to enter moth eyes. Fewer reflections or less glint from the eyes makes moths harder for predators to detect. [Moth defenses against bat echo-location is another story, for another time]

“Moths thus realize a much higher light sensitivity than butterflies, allowing a nocturnal instead of diurnal (daylight) lifestyle,” wrote Stavenga et al. “A moth with large, glittering eyes will be quite conspicuous, and therefore its visibility is reduced by the eye reflectance decreasing… The insight that nipple arrays can strongly reduce surface reflectance has been widely technically applied, e.g. in window panes, cell phone displays and camera lenses.”

Moth-eye antireflection coatings (ARCs), “which are inspired by the grainy microstructures on the corneas of moths consisting of a non-close-packed hexagonal array of conical nipples, can suppress reflection over a broader range of wavelengths and wider angles of incidence than traditional multilayer dielectric ARCs,” wrote Chih-Hung Sun and other chemical engineering colleagues at the University of Florida, Gainesville, in an article titled “Large-scale assembly of periodic nanostructures with metastable square lattices.”

Moth-eye ARCs, reported Sun et al., “are widely utilized in eliminating the “ghost images” for flat-panel displays, increasing the transmittance for optical lenses, improving the out-coupling efficiency of semiconductor light emitting diodes, and enhancing the conversion efficiency of solar cells.”

“Since all biological structures are multifunctional, it makes them even more interesting,” wrote Stanislav Gorb in his introduction to the Springer book, Functional Surfaces in Biology. “Small surface structures at the micrometer and nanometer scales (i.e. very very small) are often vitally important for a particular function or a set of diverse functions…Because of the structural and chemical complexity of biological surfaces, exact working mechanisms have been clarified only for some systems.”

Some other possible innovations from the micro-world described in the Springer book: Protective slime coatings that protect seeds from rotting (e.g. pathogens) and stimulate or inhibit seed germination as needed. Water-repellent hairs have been “invented” by spiders. Water bugs can inspire waterproofing, anti-submersion fabrics, and surfaces promoting water runoff. Self-cleaning plant surfaces that cause water to form spheres and roll off are inspiration for water-repellent surfaces that might also trap air underwater for breathing. The plant world’s system of water transport pipes (xylem) can yield ideas for water transport systems. Feather microstructures could inspire aerodynamic innovations to complement lessons learned from insect flight.

We have barely scratched the surface of the ingenious natural world that we inhabit and share.